The molar mass of copper(II) chloride (CuCl2) is 134.45 g/mol. How many formula units of CuCl2 are present in 17.6 g of CuCl2?

First convert the mass to moles: 17.6 g ÷ 134.45 g/mol = 0.1309 mol CuCl₂. Then multiply by Avogadro’s number: 0.1309 mol × 6.022 × 10²³ formula units/mol = 7.88 × 10²² formula units. The correct choice is 7.88 × 10²² formula units.

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